Particle removal apparatus and method and plasma processing apparatus

ABSTRACT

A particle removal apparatus for removing particles from a chamber of a plasma processing apparatus, wherein the chamber is connected to a gas exhaust port and a plasma of a processing gas is generated in the chamber to plasma process a substrate to be processed, includes a particle charging control member for positively charging particles generated within the chamber by positive ions of an ion sheath region formed in a region other than the vicinity of the substrate to be processed, wherein positively charged particles are discharged from the chamber via the gas exhaust port. Therefore, there is no plasma disturbance or metal contamination, and thus can be applied to a practical use.

CROSS REFERENCE

This application is a divisional of U.S. Ser. No. 10/920,367 filed Aug.18, 2004, the entire contents of which is incorporated herein byreference, and is based upon and claims priority under 35 U.S.C. 119 toJapanese Application No. 2003-298440, filed Aug. 22, 2003.

FIELD OF THE INVENTION

The present invention relates to a technology of removing particles in aprocessing apparatus for performing a film forming processing or amicroprocessing; and more particularly, to a method and apparatus ofremoving particles generated within a plasma processing apparatus.

BACKGROUND OF THE INVENTION

In a fabrication of a semiconductor device or a liquid crystal display,or the like, a substrate to be processed such as a semiconductorsubstrate, a glass substrate, or the like, is loaded into a processingvessel or a chamber of a processing device, and a film formingprocessing (chemical vapor deposition, etc.) or a microprocessing of afilm (dry etching, etc.) is performed in an airtight or a depressurizedchamber, wherein undesired particles are bound to be generated withinthe chamber. The production of these particles can be caused by thepeeling off of reaction products that have been deposited within aninner wall of the chamber, or by growth of reaction products in thechamber, wherein the reaction products are generated by reaction betweensource gases (processing gases) introduced into the chamber or between asource gas and a material to be etched. These particles generated withinthe chamber are attached to a surface of the substrate to be processed,thereby causing a reduction in a production yield or deterioration ofoperating rate of the processing apparatus. Further, the effect of theparticles on a process increases as the size of an element forming thesemiconductor device or the display device becomes small, since as thesize of the element becomes small, even a small particle as well as alarge one begins to influence the process.

Conventionally, there have been proposed several kinds of methods forremoving reaction products generated within the chamber as particles.Typically, a method for removing particles has been known, in whichparticles are collected on a negative potential electrode to therebyprevent the particles from falling onto a substrate to be processed,assuming that the particles are positively charged and generated withinthe chamber when completing a plasma etching (referring to reference 1).

FIG. 16 shows a particle-removing method disclosed in reference 1. Apair of electrodes 202 and 204 for producing a plasma is disposedparallel to each other inside a plasma etching apparatus 200, a lowerelectrode 202 is electrically connected to a high frequency power source206 with a cathode coupling arrangement, and an upper electrode 204 iselectrically grounded. In a top surface of the lower electrode 202,there is provided an electrostatic chuck electrode 212 of a positivepotential via an insulator 210, and a substrate to be processed, e.g., asemiconductor substrate 208, is mounted on the electrostatic chuckelectrode 212. A ring-shaped particle-removing electrode 214 is providedbetween the lower electrode 202 and the upper electrode 204 so as tosurround an outer periphery of a plasma generation region. During aplasma etching, a processing gas, e.g., a halogen gas or the like,introduced from a gas inlet port 216 through a shower head 218 isexcited into a plasma state between the lower electrode 202 and theupper electrode 204, and becomes a volatile gas by reaction with amaterial to be etched on a top surface of the semiconductor substrate208, to thereby be exhausted to the outside of the chamber 200 throughan exhaust port 220. The processing gas supply is stopped when theetching is completed, but positively charged particles start to fall offonce a high frequency voltage applied being turned off. Accordingly, byapplying a negative potential to the particle-removing electrode 214from a DC power source 230, the positively charged particles arecollected on the particle-removing electrode 214 of the negativepotential, thereby preventing them from reaching the semiconductorsubstrate 208.

Another typical method for removing particles of a prior art has beenknown, in which the particles are negatively charged by a plasma duringa plasma processing, and the negatively charged particles in the plasmaare removed by a collecting electrode of a positive potential providedin the vicinity of a substrate to be processed (referring to reference2). FIG. 17 describes the method disclosed in reference 2. Inside achamber (not shown) of a parallel plate type plasma etching apparatus,there are disposed a lower electrode 300 and an upper electrode 302parallel to each other, a semiconductor substrate 304 being mounted onthe lower electrode 300. Further, a hollow or a tube-shaped collectingelectrode 306 is provided in a ring shape around the lower electrode 300so as to surround the substrate 304. The collecting electrode 306 hasopenings 307 in an inner peripheral surface thereof, and is connectedthrough an exhaust pump (not shown) to outside the chamber via a gasexhaust path inside a stay 308. Preferably, in the collecting electrode306, a fine particle attraction electrode (not shown) of a positivepotential is provided inside the openings 307. Particles 312 that arenegatively charged by a plasma 310 produced between the lower electrode300 and the upper electrode 302 are collected through the openings 307inside the collecting electrode 306, and exhausted through the gasexhaust path inside the stay 308 to the outside the chamber. As aresult, theses particles 312 are prevented from being attached to thesemiconductor substrate 304.

-   [reference 1] Japanese Patent Laid-Open Application No. 2000-3902    (paragraph [0043], FIG. 11)-   [reference 2] WO 01/01467 (pages 9 and 10, FIG. 3)

In the conventional particle-removing method disclosed in reference 1,the positively charged particles are collected on the electrode of thenegative potential when the plasma processing is completed, to therebyprevent the particles from being attached to the semiconductorsubstrate. However, the present inventors examined a behavior of aparticle during a plasma processing by way of a particle measurementequipment (FIG. 4) to be mentioned later and found that particles weregenerated or existed even during the plasma processing, and further,uncharged particles, positively or negatively charged particles existedtogether (FIG. 7). This phenomenon can be evidently observed in a caseof localizing a plasma by a magnetic field or the like, particularly.That is, in such a case, a gap between an inner wall of the chamber or afacing electrode for plasma excitation (for high frequency discharge)and a plasma becomes large, so that particles generated in this regionfloat in an electrically neutral state. However, in the aforementionedprior art, the electrically neutral or negatively charged particlescannot be removed basically.

Further, in the method of reference 1, the particle-removing electrode214 of the negative potential is disposed in a region where thepositively charged particles are generated within the chamber. However,if a jig 214 of a metal member is disposed inside the chamber of theplasma processing apparatus, particularly, in the vicinity of the plasmageneration region, a plasma is disturbed, whereby controlling a plasmadistribution characteristic becomes difficult. Still further, there is aproblem that the metal member may cause a metal contamination.Therefore, it is difficult to apply such a method disclosed in reference1 to the plasma processing requiring a superior uniformity in a filmthickness or an etching rate, or a high credibility of a process.

Meanwhile, in the particle-removing method disclosed in patent reference2, the negatively charged particles during the plasma processing areremoved through the collecting electrode of the positive potential.However, even in this method, uncharged and electrically neutralparticles or positively charged particles cannot be removed basically.Further, same as reference 1, the collecting electrode 306 installed inthe vicinity of the substrate 304 to be processed significantly disturbsa plasma state, and also, may cause a metal contamination. FIG. 17 showsa main part of the parallel plate type plasma etching apparatus of acathode coupling mode. However, in a case of an anode coupling mode inwhich the lower electrode 300 is connected to a ground potential and theupper electrode 302 is connected to the high frequency power source viacapacitance coupling, a plasma is produced more closely to the vicinityof the substrate to be processed 304. Thereby, controlling plasmabecomes more difficult due to a disturbance by the collecting electrode306. Further, if a dimension or an area of the substrate to be processed304 is large, a distance between the collecting electrode 306 and acentral portion of the substrate 304 becomes large. As a result, thereis a difficulty in collecting the particles, which fall into the centralportion of the substrate. For resolving such a problem, if thecollecting electrode 306 is disposed close to the central portion of thesubstrate, a plasma disturbance becomes serious. Therefore, it isdifficult to apply this method to a practical use.

SUMMARY OF THE INVENTION

The present invention is contrived to solve the aforementioned problems.It is, therefore, an object of the present invention to provide a methodof removing particles wherein particles generated during a plasmaprocessing can be removed efficiently, there is no plasma disturbance ormetal contamination, and thus can be applied to a practical use.

In accordance with one aspect of the present invention, there isprovided a particle removal apparatus for removing particles from achamber of a plasma processing apparatus, wherein the chamber isconnected to a gas exhaust port and a plasma of a processing gas isgenerated in the chamber to plasma process a substrate to be processed,the particle removal apparatus including: a particle charging controlmember for positively charging particles generated within the chamber bypositive ions of an ion sheath region formed in a region other than thevicinity of the substrate to be processed, wherein positively chargedparticles are discharged from the chamber via the gas exhaust port.

In accordance with another aspect of the present invention, there isprovided a particle removal apparatus for removing particles from achamber of a plasma processing apparatus, wherein the chamber isconnected to a gas exhaust port and a plasma of a processing gas isgenerated in the chamber to plasma process a substrate to be processed,the particle removal apparatus including: a particle charging controlmember for positively charging particles generated within the chamber bypositive ions of an ion sheath region formed in a region other than thevicinity of the substrate to be processed; and a charged particletransfer member for transferring positively charged particles towardsthe gas exhaust port via the ion sheath region.

In the present invention, it is preferred that the particle chargingcontrol member has a control electrode installed to face the plasma withthe ion sheath region therebetween and a power supply unit supplying thecontrol electrode with a negative potential, or at least one of theparticle charging control member and the charged particle transfermember has a control electrode disposed facing the plasma and a powersupply unit supplying the control electrode with a negative potential.By such a configuration, the particles generated within the chamber andthermally moving around the chamber can be efficiently chargedpositively by the positive ions in the ion sheath region of theelectrode side facing with the substrate to be processed or an innerwall side of the chamber.

Further, it is preferred that the control electrode is installed, via aninsulating film, on a surface of a second high frequency dischargeelectrode disposed to face a first high frequency discharge electrode onwhich the substrate to be processed is mounted, or the control electrodeis provided in an inner wall surface of the chamber via an insulatingfilm. By doing this, the particle removal apparatus of the presentinvention does not have a bad influence on the plasma generation and hasa simple configuration, so that the apparatus can be applied to apractical use.

Still further, the control electrode may have a plurality of conductorsphysically separated from each other, and the power supply unit suppliesthe conductors with independent negative potentials. In this case, it ispreferred that the power supply unit supplies a negative potential witha greater absolute value to a conductor disposed closer to the gasexhaust port. By such a configuration, the positively charged particlescan be drift transferred towards the gas exhaust port, to thereby bedischarged with a high efficiency.

Still further, the power supply unit may supply the conductors withpulses of negative potentials with a phase relationship allowing thepositively charged particles to be sequentially transferred towards thegas exhaust port. By doing this, the particles to be collected betweenthe plasma and the control electrode by a repulsive Coulomb force fromthe plasma PZ having a positive electric potential and an attractiveCoulomb force from the control electrode, as mentioned above, can beefficiently transferred from the central portion to the periphery of thechamber. In addition, the particles reaching the inner wall side of thechamber can be delivered to the gas exhaust port with a high efficiency.

Meanwhile, the power supply unit may have a DC power source electricallyconnected to the control electrode via a DC circuit, or have a highfrequency power source electrically connected to the control electrodevia capacitance coupling. Further, a surface of the control electrodemay be coated with an insulating film. If the surface of the controlelectrode is coated with the insulating film, there is no metalcontamination. Therefore, a plasma processing can be performed with ahigh credibility.

Further, the plasma processing apparatus of the present invention mayhave a magnetic field forming member for localizing the plasma producedin the chamber around the substrate to be processed. In this case, aspace region facing the substrate to be processed with the plasmatherebetween inside the chamber becomes large. By installing the controlelectrode of the particle charging control member or the particletransfer member in the space region, the plasma is less likely to bedisturbed.

In accordance with still another aspect of the present invention, thereis provided a method of removing particles from a chamber of a plasmaprocessing apparatus, wherein the chamber is connected to a gas exhaustport and a plasma of a processing gas is generated in the chamber toplasma process a substrate to be processed, the method including thesteps of: positively charging particles generated within the chamber bypositive ions of an ion sheath region formed in a region other than thevicinity of the substrate to be processed; guiding positively chargedparticles towards the gas exhaust port via the ion sheath region; anddischarging the positively charged particles from the chamber throughthe gas exhaust port.

In the present invention, it is preferred that a negative potential isapplied to a surface of an object disposed adjacent to the ion sheathregion in order to attract positive ions and the positively chargedparticles towards the surface of the object. Further, it is preferredthat the object adjacent to the ion sheath region is electricallydivided into a plurality of regions depending on a distance from the gasexhaust port, and independent negative potentials are applied to therespective regions. Wherein, a negative potential with a greaterabsolute value may be applied to a region closer to the gas exhaustport. Still further, a number of negative potentials with differentpulse phases may be applied to the plurality of regions, to transfer thepositively charged particles towards the gas exhaust port. By doingthis, the positively charged particles can be efficiently drifttransferred towards the gas exhaust port, and be easily discharged fromthe chamber. In addition, the attachment of the particles to thesubstrate to be processed can be suppressed.

Meanwhile, in accordance with a following method of removing particles,negative voltages of periodic pulses, whose phases are deviated fromeach other, are applied in a plurality of regions forming a controlelectrode, and positively charged particles are transferred towards agas exhaust port. By doing this, particles can be very efficientlytransferred, particularly, from a central portion to a periphery of thechamber to thereby further improve a removal efficiency of theparticles.

In accordance with still another aspect of the present invention, thereis provided a method of removing particles from a chamber of a plasmaprocessing apparatus, wherein the chamber is connected to a gas exhaustport and a plasma of a processing gas is generated in the chamber toplasma process a substrate to be processed, the method including thesteps of: positively charging particles by positive ions of an ionsheath region formed along an inner wall of the chamber; guidingpositively charged particles towards the gas exhaust port along theinner wall of the chamber; and discharging the positively chargedparticles from the chamber through the gas exhaust port. In such amethod of removing particles, it is preferred that a control electrodeembedded in an insulator is provided on the inner wall of the chamber,and a negative potential for attracting the positive ion and thepositively charged particles toward the inner wall of the chamber isapplied to the control electrode.

In accordance with still another aspect of the present invention, thereis provided a method of removing particles from a chamber of a plasmaprocessing apparatus, wherein the chamber is connected to a gas exhaustport and a plasma of a processing gas is generated within the chamber byapplying a high frequency power between a first and a second electrodedisposed in the chamber to face each other to plasma process a substrateto be processed placed on the first electrode, the method including thesteps of: positively charging particles by positive ions of an ionsheath region formed along the second electrode; guiding positivelycharged particles towards the gas exhaust along a main surface of thesecond electrode and an inner wall of the chamber; and discharging thepositively charged particles from the chamber through the gas exhaustport.

In the aforementioned method of removing particles, a control electrodeembedded in an insulator may be provided on the main surface of thesecond electrode and a negative voltage for attracting the positive ionsand the positively charged particles towards the main surface of thesecond electrode may be applied to corresponding control electrode.

Further, in the aforementioned methods of removing particles, the gasexhaust port may be disposed around a lower part of the inner wall ofthe chamber and the positively charged particles may be guided towardsthe gas exhaust port while moving down along the inner wall of thechamber. Otherwise, a baffle plate for providing a gas exhaust path of alow conductance may be installed in the vicinity of an entrance side ofthe gas exhaust port, and a negative potential is applied to the baffleplate. By doing this, the positively charged particles can beefficiently drift transferred towards the gas exhaust port, to therebybe discharged from the chamber with high speed.

In accordance with still another aspect of the present invention, thereis provided a plasma processing apparatus having a chamber connected toa gas exhaust port, wherein a plasma of a processing gas is generatedwithin the chamber to plasma process a substrate to be processed, theplasma processing apparatus including: a particle charging controlmember for positively charging particles generated within the chamber bypositive ions of an ion sheath region formed in a region other than thevicinity of the substrate to be processed, wherein positively chargedparticles are discharged from the chamber via the gas exhaust port.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects and features of the present invention willbecome apparent from the following description of preferred embodimentsgiven in conjunction with the accompanying drawings, in which:

FIG. 1 shows a configuration of a plasma etching apparatus adopting aparticle removal apparatus in accordance with a first preferredembodiment of the present invention;

FIG. 2 describes a time sequence for explaining an operation of aparticle removal apparatus in accordance with the first preferredembodiment of the present invention;

FIG. 3 illustrates a graph of typically showing an electric potentialdistribution while producing a plasma for explaining an operation of aparticle removal apparatus in accordance with the present invention;

FIG. 4 offers a configuration of a particle measurement equipment forverifying an effect of the present invention;

FIG. 5 is a view for typically showing a particle trajectory inside achamber for explaining an operation and effect in accordance with thefirst preferred embodiment;

FIG. 6 provides a graph for showing a time sequence variation of thenumber of particles measured by a particle measurement equipment in thefirst preferred embodiment;

FIG. 7 presents a graph for showing a time sequence variation of thenumber of particles measured by a particle measurement equipment, whenthe present invention is not applied;

FIG. 8 depicts a distribution map of an in-surface etching rate of asilicon substrate when plasma etching a silicon oxide film in the firstpreferred embodiment;

FIG. 9 represents a configuration of a plasma etching apparatus adoptinga particle removal apparatus in accordance with a second preferredembodiment of the present invention;

FIG. 10 sets forth a time sequence for explaining an operation of aparticle removal apparatus in accordance with a second preferredembodiment;

FIG. 11 shows a configuration of a plasma etching apparatus adopting aparticle removal apparatus in accordance with a third preferredembodiment of the present invention;

FIG. 12 describes a time sequence for explaining an operation of aparticle removal apparatus in accordance with the third preferredembodiment;

FIG. 13 illustrates a configuration of a plasma etching apparatusadopting a particle removal apparatus in accordance with a fourthpreferred embodiment of the present invention;

FIG. 14 offers a time sequence for explaining an operation of a particleremoval apparatus in accordance with the fourth preferred embodiment;

FIG. 15 is a view for typically showing a particle trajectory inside achamber for explaining an operation and effect in accordance with thefourth preferred embodiment;

FIG. 16 provides a configuration of a plasma etching apparatus having aparticle removal apparatus of a prior art; and

FIG. 17 presents a particle removal apparatus of another prior art.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, preferred embodiments of the present invention will bedescribed in detail with reference to the accompanying drawings.

FIG. 1 shows a configuration of a plasma processing apparatus having aparticle removal apparatus in accordance with a first preferredembodiment of the present invention. The plasma processing apparatus isa parallel plate type RIE plasma etching apparatus, and has acylindrical chamber (processing vessel) 10 made of a metal, e.g.,aluminum, stainless, or the like. The chamber 10 is frame grounded.

In the chamber 10, there is installed a disk-shaped lower electrode or asusceptor 12 on which a substrate to be processed, e.g., a semiconductorwafer W, is mounted. The susceptor 12 is made of, e.g., aluminum, andsupported by a tube-shaped supporter 16, which is vertically extendedupward from a bottom of the chamber 10, via an insulating andtube-shaped holder 14. In a top surface of the tube-shaped supporter 16,there is disposed a focus ring 18 made of, e.g., a quartz, and annularlysurrounding a top surface of the susceptor 12.

A gas exhaust path 20 is formed between a sidewall of the chamber 10 andthe tube-shaped holder 14, and an annular baffle plate 22 is provided inan inlet port or an inside of the gas exhaust path 20 and, at the sametime, a gas exhaust port 24 is installed in a bottom portion. A gasexhaust apparatus 28 is connected to the gas exhaust port 24 via the gasexhaust path 26. The gas exhaust apparatus 28 has a vacuum pump, and candepressurize an inside of the chamber 10 up to a predetermined vacuumlevel. In the sidewall of the chamber 10, there is provided a gate valve30 for opening/closing a loading/unloading port of the semiconductorwafer W.

A high frequency power source 32 for producing a plasma and RIE iselectrically connected to the susceptor 12 via a matching unit 34. Thehigh frequency power source 32 applies a predetermined high frequency,e.g., a high frequency power of 60 MHz, to the lower electrode, i.e.,the susceptor 12. In a ceiling of the chamber, there is installed ashower head 38 that will be described later, as an upper electrode of aground potential. A high frequency voltage from the high frequency powersource 32 is applied between the susceptor 12 and the shower head 38.

An electrostatic chuck 40 for holding the semiconductor wafer W byelectrostatic adsorptive force is provided in a top surface of thesusceptor 12. An electrode 40 a made of a conductive film is embeddedbetween a pair of insulating films 40 b in upper and lower sides of theelectrode 40 a, and a DC power source 42 is electrically connected tothe electrode 40 a via a switch 43. By a DC voltage from the DC powersource 42, the semiconductor wafer W can be adsorbed and held on thechuck by Coulomb force.

Inside the susceptor 12, a coolant passageway 44 spreading, e.g., in acircumferential direction is installed. A coolant, e.g., a coolingwater, kept at a predetermined temperature is circulated and suppliedinto the coolant passageway 44 via the lines 48 and 50 from a chiller(cooler) unit 46. Further, a heat transfer gas, e.g., a He gas, from aheat transfer gas supply unit 52 is supplied between the top surface ofthe electrostatic chuck 40 and a rear surface of the semiconductor waferW via a gas supply line 54.

The shower head 38 of the ceiling has an electrode plate 56 having aplurality of gas passing holes 56 a, in a lower surface thereof, and anelectrode supporting body 58 for supporting the electrode plate 56 suchthat the electrode 56 can be attached thereto or detached therefrom.Here, the electrode supporting body 58 has a plurality of gas passingholes 58 a connected with the gas passing holes 56 a of the electrodeplate 56. A buffer chamber 60 is installed inside the electrodesupporting body 58, and a gas supply line 64 from a processing gassupply unit 62 is connected to a gas inlet port of the buffer chamber60.

An annularly or concentrically spreading magnet 66 is disposed aroundthe chamber 10. Inside the chamber 10, an RF electric field is formed ina vertical direction by the high frequency power source 32 in a spacebetween the shower head 38 and the susceptor 12. By high frequencydischarge, it is possible to produce a plasma of high density in thevicinity of a surface of the susceptor 12.

An etcher controller 68 functions to control an operation of each unitinside the plasma etching apparatus such as a gas exhaust unit 28, thehigh frequency power source 32, the switch 43 for electrostatic chuck,the chiller (cooler) unit 46, the heat transfer gas supply unit 52, theprocessing gas supply unit 62, a control unit of the particle removalapparatus (e.g., charging controller 74) that will be described later,and the like, and is connected to an external apparatus, e.g., a hostcomputer (not shown).

In this plasma etching apparatus, an etching is performed in such amanner that first, a gate valve 30 is opened, and a semiconductor waferW as an object to be processed is loaded into the chamber 10 and mountedonto the electrostatic chuck 40. Then, a processing gas, i.e., anetching gas, is introduced into the chamber 10 at a predetermined flowrate from the processing gas supply unit 62, and an inner pressure ofthe chamber 10 is set at a set value by adjusting the gas exhaust unit28. Further, a predetermined high frequency power is supplied into thesusceptor 12 from the high frequency power source 32. Still further, aDC voltage is applied to the electrode 40 a of the electrostatic chuck40 from the DC power source 42 to adhere the semiconductor wafer W onthe electrostatic chuck 40. An etching gas discharged from the showerhead 38 is converted into a plasma state by high frequency dischargebetween the electrodes 12 and 38, and a main surface of thesemiconductor wafer W is etched by a radical or an ion generated in theplasma.

The particle removal apparatus in accordance with this embodimentincludes a charging electrode 72 equipped in an inner wall of thechamber 10 or the shower head (upper electrode) 38 having a film-shapedinsulator 70 therebetween; and a charging controller 74 to control thecharging of a particle in the chamber 10 through the charging electrode72. The charging electrode 72 is made of a film-shaped or a sheet-shapedconductor, e.g., aluminum, stainless steel, or the like. A negativepotential from the charging controller 74 is applied to the chargingelectrode 72. The insulator 70 is made of, e.g., alumina for which asurface of aluminum is alumite treated, or ceramic obtained by thermallyspraying yttria (Y₂O₃) to a conductor, wherein entire surfaces (innerand outer surfaces) of the charging electrode 72 are coated therewith.Meanwhile, in the inner wall surface of the shower head (upperelectrode) 38, openings connected with the gas discharge openings 56 agoing through the electrode plate 56, the charging electrode 72 and theinsulator 70 are installed. Preferably, the charging controller 74includes a variable output voltage DC power source, and is configured tocontrol a potential of the charging electrode 72 and an application timeof a voltage, under the control of the etcher control unit 68.

As described above, in this embodiment, there is installed the chargingelectrode 72 that is attached or connected to the inner wall of thechamber 10 or the shower head 38 having the film-shaped insulator 70therebetween. However, it can be configured such that the inner wall of,e.g., aluminum made chamber 10 or the shower head 38 is alumite treatedto have a control voltage applied thereto, that is, the chamber 10 orthe shower head 38 serves as a charging electrode.

FIG. 2 describes one example for an application time of a chargingcontrol voltage to charging electrode 72 from the charging controller74. In this example, a charging control voltage begins to be applied tothe charging electrode 72 right before the processing gas is introducedinto the chamber 10, and after completing the etching, i.e., after anelapse of a predetermined time from stopping supplying the processinggas and the high frequency power, applying the charging control voltageis stopped to return the potential of the charging electrode 72 to theground potential.

It is preferable that the charging control voltage applied to thecharging electrode 72 is of a large absolute value so as to sufficientlycharge the particles. However, if the applying voltage (absolute value)is too large, abnormal discharge is developed between the chargingelectrode 72 and a plasma, between the charging electrode 72 and thechamber 10, or the like, or the plasma may be affected by the voltageapplied to the charging electrode 72. Therefore, it is preferable thatthe charging control voltage is set within a range, e.g., about −10V˜−500 V such that a current running through the charging electrode 72becomes sufficiently small (e.g., about 0.1 A) to thereby prevent suchan undesirable phenomenon.

Next, an operational principle of a particle removal method inaccordance with the embodiment (more generally, the present invention)will be discussed with reference to FIGS. 1 and 3.

FIG. 3 is a graph for typically showing an electric potentialdistribution in a vertical direction in a plasma generation regionbetween the lower electrode (susceptor) 12 and the upper electrode(shower head) 38 of the plasma etching apparatus (FIG. 1). In thisplasma generation region, a plasma is produced by a so-called cathodecoupling mode. In this graph, there is shown an electric potentialdistribution, in case where a negative voltage (e.g., −200 V) is appliedto the charging electrode 72. As shown in FIG. 3, if the negativevoltage (−200 V) is applied to the charging electrode 72, a particlecharging region 76 is formed between a plasma PZ (FIG. 1) and thecharging electrode 72 inside the upper electrode 38 (further exactly,inner side of the insulator 70). The particle charging region 76 meansan ion sheath where an electric field by the negative potential of thecharging electrode 72 is strengthened and many positive ions arepresent. Inside the chamber 10, particularly, many floating neutralparticles produced in the plasma generation region becomes positivelycharged by colliding with the positive ions running toward the chargingelectrode 72 in the particle charging region 76. The positively chargedparticles are repelled from the plasma PZ of the positive potential andguided towards the charging electrode 72 of the negative potential byCoulomb force, to thereby move around the particle charging region whilecolliding with a surface of the insulator 70 inside the chargingelectrode 72 to be scattered therein. Meanwhile, as shown in FIG. 1, theparticles indicated by ‘O’ finally reach the vicinity of the sidewallpart of the chamber 10. In that region, the particles, while being underthe influence of the attractive Coulomb force from the chargingelectrode 72 inside the chamber sidewall, are accelerated downward bythe gravitational force along the flow of the exhaust gas and passthrough the baffle plate 22, to thereby be exhausted from the chamber 10through the gas exhaust port 24.

In the etching apparatus of this embodiment, to apply a horizontalmagnetic field to the substrate W to be processed by the ring-shapedmagnet 66, the plasma PZ is localized towards the substrate W to beprocessed. As mentioned above, if the plasma PZ is formed away from thecharging electrode 72 inserted into the inner wall of the chamber 10,the plasma is less likely to be disturbed due to the application of thenegative voltage to the charging electrode 72 so that it is possible tocontrol the plasma more easily. In the present invention, it gets easierto charge a particle as the size thereof gets larger, but a particle ofa size of several nm can be sufficiently charged in the particlecharging region 76, as well. Further, such a localization of the plasmacan be achieved by using a helicon wave plasma generation, ECR (ElectronCyclotron Resonance) plasma generation, or ICP (Inductive CoupledPlasma) plasma generation, instead of the magnetic field.

Next, an operation and effect of the present embodiment will bediscussed in the following example with reference to FIGS. 4 to 8. Inthis example, the particle measurement equipment shown in FIG. 4 wasused so as to exactly understand the particle generation within thechamber 10. As shown in FIG. 4, a quartz window 80 was provided in apart of the chamber 10 and the ring-shaped magnet 66. A laser beam 84having a flat beam section was incident on the vicinity of the upperside of the semiconductor wafer W in parallel with the surface thereof,via the quartz window 80 from a light source of the laser controller 82.If there was a particle present, a scattered light of the laser beam wascontinuously photographed by a CCD camera 86. Here, the laser beam 84was extinguished by a light extinction unit 88 in order to eliminate anoise of the scattered light. A CPU 90 served to monitor an operationtiming of the plasma processing apparatus by the etcher controller 68and, at the same time, control a laser emission of the laser controller82 and data process image information obtained by the CCD camera 86. Inthis example, by using such a particle measurement equipment, theparticle generated during the operation of the plasma processingapparatus was measured in a real-time.

As for the substrate to be processed, a semiconductor wafer W having adiameter of 200 mmφ was used, and an etching of a silicon oxide film andparticle removing were performed by following the time sequence as givenin FIG. 2. More particularly, an inside of the chamber 10 wasdepressurized to a high vacuum of about 10⁻⁵ Pa, and then, a DC voltageof −200 V was applied to the charging electrode 72 from the chargingcontrol unit 74. Thereafter, a gaseous mixture of C₄F₈/Ar/O₂ wasintroduced into the chamber 10 as an etching gas of a processing gas tothereby maintain an inner pressure of the chamber 10 at about 5 Pa, andan RF power of 60 MHz and 1500 W was supplied to produce a plasma ofcorresponding etching gas. Therefore, a plasma etching was performed onthe silicon oxide film on the semiconductor wafer W. Meanwhile, amagnetic flux density obtained by the ring-shaped magnet 66 was about100 Gauss in the vicinity of a top surface of the semiconductor wafer W.After performing the etching for 1 minute, the gas and the RF power werestopped to be supplied. After 10 seconds, the potential of the chargingelectrode 72 returned to a ground potential, and after 10 secondsthereafter, the gate valve 66 was opened to transfer the semiconductorwafer W to a load-lock chamber of a neighboring chamber.

In case when performing a plasma etching processing described above,effects of the present invention on particle removal can be described asfollows. FIG. 5 typically shows a particle trajectory obtained in areal-time measurement by the particle measurement equipment (FIG. 4). Asshown in FIG. 5, the plasma PZ was produced in an upper part of thesemiconductor wafer W, which was electrostatically adsorbed on theinsulating film 40 b of a surface of the electrode 40 a in theelectrostatic chuck 40, and the particle charging region 76 was formedbetween the plasma PZ and the insulator 70 on the surface of thecharging electrode 72. Further, it was confirmed that a plurality ofparticle trajectories 92 was present in the particle charging region 76.This means that an electrically neutral particle collided with apositively charged ion in the ion sheath region (particle chargingregion 76) where an electric field was strengthened by the chargingelectrode 72 of the negative potential (−200 V), which was insulated andseparated by the insulator 70 b from the upper electrode plate 56 keptat the ground potential, and became positively charged after beingcombined with the positively charged ion to thereby move around theregion. Further, the number of particles moving in the particle chargingregion 76 did not change much while producing the plasma. Meanwhile,simultaneously, a large number of particles reached the sidewall part ofthe chamber 10, as mentioned above, and was discharged downward alongthe sidewall part. Namely, in the present invention, the electricallyneutral particle was positively charged continuously in the ion sheathregion (particle charging region 76) where the field intensity wasstrengthened by the charging electrode 72 in the inner wall part (upperand side walls) of the chamber 10, and the positively charged particleswere discharged from the chamber 10 through the ion sheath regionextending downward along the sidewall part of the chamber 10.

Further, the number of particles floating in the vicinity of the topsurface of the semiconductor wafer W during the etching processing wasmeasured and examined. FIG. 6 is a graph for showing a result in a caseof adopting the particle removal apparatus of the present invention, andFIG. 7 is for a case (reference example) when the particle removalapparatus of the present invention was not used in the same plasmaprocessing apparatus as FIG. 6. In FIGS. 6 and 7, a horizontal axiscorresponds to a time axis of time sequence in the etching processing,and a vertical axis corresponds to the number of particles indicated as‘●’ mark.

In the present invention, the processing gas and the RF power wereprovided in the same sequence as that in FIG. 2, and no particles wereobserved in the vicinity of the top surface of the semiconductor wafer Wwhile the charging controller was operated (i.e., while a chargingcontrol voltage was applied to the charging electrode 72), as known fromFIG. 6. On the other hand, in FIG. 7, the particles began to appear whenthe processing gas was introduced, and had been observed throughout theetching processing even though the number of particles varied somewhat.This means that in accordance with the present invention, the number ofparticles generated during the etching processing and attached to thesubstrate to be processed can be substantially reduced by positivelycharging the particles and removing them. Generally, it is consideredthat there are particles charged negatively by a plasma during theplasma processing, as well. However, in the etching processing of thepresent invention, the negatively charged particles were not generated,and if any, a very small amount of particles was generated.

Meanwhile, it is confirmed that the plasma disturbance caused byoperating the particle removal apparatus of the present invention is ofan ignorable level. FIG. 8 shows an etching rate characteristic, whereina solid line is for the present invention and a dot line is for thereference example in which the particle removal apparatus of the presentinvention is not adopted. As is clear from FIG. 8, the etching rate doesnot vary within an error range. As mentioned above, the particle removalapparatus of the present invention does not affect the plasmadistribution characteristic of the plasma processing apparatus and caneffectively remove the particle generated within the chamber 10.Further, the particle removal apparatus of the present invention isconfigured to have the charging electrode 72 and the insulator 70, whichare equipped in the inner wall of the chamber in the plasma processingapparatus, and the charging controller 74 outside the chamber, and canremove the particle in a very simple way. Therefore, the particleremoval apparatus of the present invention can find a high applicabilityin a wide range of field. Meanwhile, the aforementioned exampledescribes an etching of the silicon oxide film but CVD (chemical vapordeposition) thereof or the like can be performed in the completely samemanner.

Second Embodiment

FIG. 9 shows a configuration of a plasma etching apparatus having aparticle removal apparatus in accordance with a second preferredembodiment of the present invention. In the drawing, like referencenumerals will be assigned to like parts having substantially sameconfigurations or functions, and redundant description thereof will beomitted in the specification and the accompanying drawings. Here, acharacteristic feature of the second preferred embodiment will bediscussed mainly. In the second preferred embodiment, a member forperforming a drift transfer on a positively charged particle in aparticle charging region 76, same as in the aforementioned firstembodiment, is included, so that a particle can be discharged outsidethe chamber further efficiently.

As shown in FIG. 9, a first charging electrode 102 embedded in afilm-shaped insulator 100 is installed in an inner wall of the ceilingof a chamber 10 containing the inner wall surface of an electrode plate56 of a shower head 38. A negative voltage is applied to the firstcharging electrode 102 from a first control unit 104. It is preferablethat the first control unit 104 has a variable output voltage DC powersource, and controls a potential of the first charging electrode 102 anda timing of applying a voltage under the control of an etcher controlunit 68 (FIG. 1). The first charging electrode 102 and the first controlunit 104 serve as a particle charging control member, mainly.

Further, a second charging electrode 106 embedded in the insulator 100is installed in the inner side of the sidewall of the chamber 10. Anegative voltage is applied to the second charging electrode 106 from asecond control unit 108. It is preferable that the second chargingelectrode 106 has a variable output voltage DC power source, andcontrols a potential of the second charging electrode 106 and a timingof applying a voltage under the control of the etcher control unit 68(FIG. 1). The second charging electrode 106 and the second control unit108 serve as a particle transfer member, mainly. Meanwhile, the firstand the second charging electrode 102 and 106 may be formed of afilm-shaped or a sheet-shaped conductor such as aluminum, stainlesssteel, or the like. The insulator 100 is made of a film-shaped ceramic,e.g., alumina that, e.g., an aluminum surface is alumite treated, andentire surfaces (inner and outer surfaces) of the first and the secondcharging electrode 102 and 106 are coated therewith.

FIG. 10 shows a time sequence in this embodiment. When performing aplasma etching, it is preferred that the negative voltages (the firstand the second control voltage) begin to be applied to the first and thesecond charging electrode 102 and 106 from the first and second controlunits 104 and 108, respectively, right before introducing the processinggas into the chamber 10. Here, it is preferred that an absolute value ofthe negative voltage applied to the second charging electrode 106 (thesecond control voltage) is set to be greater than that of the firstcharging electrode 102 (the first control voltage). For example, −100 Vand −200 V may be applied to the first and the second charging electrode102 and 106, respectively. Same as in the first embodiment, the negativevoltages (the first and the second control voltage) are continuouslyapplied to the first and the second charging electrode 102 and 106during the etching processing, as well. Further, after completing theetching processing and thus stopping supplying the processing gas andthe high frequency power, application of the negative voltage (the firstcontrol voltage) to the first charging electrode 102 is stopped first.Subsequently, after an elapse of a predetermined time, it is preferredthat the application of the negative voltage (the second controlvoltage) to the second charging electrode 106 is stopped.

Like in the first embodiment, a particle is generated within the chamber10 during the plasma etching, and the particle charging region 76 isformed between the plasma PZ and the first charging electrode 102 (moreprecisely, inner side of the insulator 70) under the electrode plate 56,by the application of the negative voltage (the first control voltage)to the first charging electrode 102. As a result, the particle generatedduring the plasma etching collides with the positively charged ion inthe particle charging region 76 and is combined therewith to therebybecome positively charged. The positively charged particle moves in theparticle charging region 76, while a repulsive Coulomb force from theplasma PZ having a positive electric potential is exerted thereon and anattractive Coulomb force from the first charging electrode 102 of thenegative potential is applied thereto at the same time. Further, asshown in FIG. 9, the particles 110 moving away from the plasma PZ abovethe substrate W to be processed towards the end of the first chargingelectrode 102 are forced to be drift transferred to the sidewall of thechamber by the attractive Coulomb force from the second chargingelectrode 106 of the sidewall of the chamber. As mentioned above, bymaking the absolute value of the negative potential of the secondcharging electrode 106 greater than that of the first charging electrode102, it is possible to perform the drift transfer strongly andeffectively. The particles, which are transferred to the inner side ofthe sidewall of the chamber 10, are accelerated downward by thegravitational force along the flow of the exhaust gas and pass through abaffle plate 22, to thereby be exhausted from the chamber 10. Therefore,in accordance with the second preferred embodiment, it is possible toremove the particle within the chamber 10 more efficiently, as comparedwith the first embodiment.

Third Embodiment

FIG. 11 shows a configuration of a plasma etching apparatus having aparticle removal apparatus in accordance with a third preferredembodiment of the present invention. In the drawing, the same referencenumerals with those of the first and the second embodiment (FIGS. 1 and9) will be assigned to like parts having substantially sameconfigurations or functions, and redundant description thereof will beomitted in the specification and the accompanying drawings. Here, acharacteristic feature of the third preferred embodiment will bediscussed mainly. In the third embodiment, means or a method for moreforcibly transferring or delivering the particles charged positively ina particle charging region 76 is included, so that the particles can bedischarged outside a chamber 10 more efficiently, as compared with thesecond embodiment.

As shown in FIG. 11, an upper charging electrode 102 is divided into acentral charging electrode 102A and a peripheral charging electrode 102Bin a diametrical direction, wherein the upper charging electrode 102 isinstalled in the inner wall surface of the ceiling of the chamber 10containing the inner wall of an electrode plate 56 of a shower head(upper electrode) 38. For example, it is preferable that a plane shapeof the central charging electrode 102A is a circle and that of theperipheral charging electrode 102B is a ring shape of a concentriccircle with the central charging electrode 102A. A first control unit104 is configured such that respective negative voltages (first controlvoltages A and B) are independently applied to the central chargingelectrode 102A and the peripheral charging electrode 102B while having apredetermined specific timing relation (phase difference) therebetween.Further, the central charging electrode 102A, the peripheral chargingelectrode 102B, and the first control unit 104 are configured to serveas particle charging control means and particle transfer means.

Further, a second charging electrode 106 embedded in an insulator 100 isinstalled in the inner wall of the chamber 10. Same as in the secondembodiment, a second control unit 108 controls a potential of the secondcharging electrode 106 and a timing of applying a voltage. Meanwhile, itcan be configured such that the first and the second control unit 104and 108 receive control signals from an etcher control unit 68 (FIG. 1),respectively, and at the same time, send and receive the control signalstherebetween so as to match a timing of applying each voltage.

FIG. 12 shows a time sequence of this embodiment. The sequence of theplasma processing itself is the same as those of the first and thesecond embodiment. Namely, a processing gas is supplied into the chamber10, and then, an RF power is applied to a susceptor 12 from a highfrequency power source 32 to produce a plasma PZ of a correspondingprocessing gas. In this embodiment, negative voltage pulses of differentphases from each other, i.e., the first control voltages A and B, areapplied to the central charging electrode 102A and the peripheralcharging electrode 102B, respectively, from the first control unit 104,with the same timing as that shown in FIG. 12. In such a case, it may beconfigured such that a pulse output to the central charging electrode102A is started first, from the first control voltage A, and a pulse ofthe second control voltage B to the peripheral charging electrode 102Bis outputted at the last time. In FIG. 12, a phase difference betweenthe first control voltages A and B is set about 180°, but any phasedifference may be selected. Here, it is preferred that an absolute valueof the negative potential of the first control voltage B is set to begreater than that of the first control voltage A, for example, A=−100 Vand B=−200 V.

The particles generated during the plasma etching are positively chargedin the particle charging region 76 in the vicinity of the centralcharging electrode 102A and the peripheral charging electrode 102B. Thepositively charged particles move around in the particle charging region76, while being repulsed from the plasma PZ having a positive electricpotential by Columbic force and, at the same time, being attracted fromthe first charging electrode 102 of the negative potential by Columbicforce. Further, in this case, since the negative voltages of rectangularperiodic pulses, whose phases are deviated from each other, are applied,the positively charged particles 112 (FIG. 11) under the centralcharging electrode 102A are attracted towards the peripheral chargingelectrode 102B and delivered thereto during a time zone when the firstcontrol electrode A becomes of a low level (ground potential) and thefirst control electrode B becomes of a high level (−200 V), as shown inFIG. 12. Such a particle transfer can be performed more effectively byrepeatedly applying the negative voltages A and B whose phases aredeviated from each other. Therefore, the whole positively chargedparticles formed in the central area of the ceiling on the chamber 10are transferred to the peripheral side thereof.

Further, the second control voltage from the second control unit 108 isapplied to the second charging electrode 106 in a predetermined timingwith respect to the pulse apply control of the first control voltages Aand B by the first control unit 104 mentioned above (FIG. 12). Here, anabsolute value of the negative potential of the second chargingelectrode 106 is set to be greater than that of first control voltage B.For example, if the first control voltage B is −200 V, the secondcontrol voltage may be −300 V. By doing this, the particles 110 reachingthe peripheral charging electrode 102B are forced to be drifttransferred to the sidewall of the chamber by a strong attractive forcefrom the second charging electrode 106, which is installed in thesidewall part of the chamber.

After stopping supplying the processing gas and the high frequencypower, in order to complete the plasma etching processing, it can beconfigured such that the negative voltages (the first control voltage Band the second control voltage) are continuously applied to theperipheral charging electrode 102B and the second charging electrode 106for a predetermined time, and the positively charged particles are keptbeing delivered and transferred (FIG. 12). Therefore, the particlesgenerated within the chamber 10 are gravitationally accelerated downwardalong the flow of the exhaust gas, and pass through the baffle plate 22,to thereby be discharged from the chamber 10 through the gas exhaustport 24.

In accordance with the third embodiment, it is possible to remove theparticles generated in a substantially central part of the ceiling ofthe chamber 10 more efficiently, as compared with the second embodiment.Further, such an effect can be further increased as the diameter of thecylindrical chamber 10 becomes large. Meanwhile, even in case where thenegative voltages of the first control voltages A and B are set at asame value with each other, the particles can still be transferred eventhough the efficiency thereof is reduced a little.

Fourth Embodiment

FIG. 13 shows a configuration of an apparatus in accordance with afourth embodiment. The fourth embodiment is same as the third one,except that two characteristic features are added. The firstcharacteristic feature is that a DC positive voltage is applied to asubstrate W side (e.g., the electrode 40 a of an electrostatic chuck 40)to thereby repel a positively charged particle therefrom in order toprevent the falling of the positively charge particle onto a substrate Wto be processed. For this, a variable output voltage DC power source 114is electrically connected to an electrostatic chuck electrode 40 a on asusceptor 12, via a low-pass filter 116. Here, the low-pass filter 116functions to cut off a high frequency from a high frequency power source32.

A second characteristic feature is that the particle removing isfacilitated by applying a negative voltage to a baffle plate 22 disposedin an opening of a gas exhaust path 20 in a bottom part of a chamber 10.In FIG. 13, a negative voltage B (the second control voltage) is appliedto the baffle plate 22 from a second control unit 108. Here, it ispreferred that an absolute value of the second control voltage B appliedto the baffle plate 22 is set to be greater than that of the secondcontrol voltage A for the second charging electrode 106. For example, ifthe second control voltage A is −300 V, the second control voltage B maybe set to −400 V. Meanwhile, an insulating material (not shown) isinstalled between the baffle plate 22 and the sidewall of the chamber 10so as to electrically insulate them from each other.

FIG. 14 shows a time sequence of the fourth embodiment. As shown in FIG.14, it is configured such that a second control voltage B for the baffleplate 22 is added to the sequence (FIG. 12) of the third embodiment.Preferably, the second control voltage B is applied to the baffle plate22 with a predetermined phase difference from the second control voltageA for the second charging electrode 106 (i.e., waiting a little while).Accordingly, positively charged particles 118 are drift transferred tothe baffle plate 22 from the sidewall of the chamber. As shown in FIG.14, after stopping supplying the processing gas and the high frequencypower in order to complete the plasma etching processing, the negativevoltages are applied to the peripheral charging electrode 102B, thesecond charging electrode 106, and the baffle plate 22 (the firstcontrol voltage B, the second control voltage A, and the second controlvoltage B), respectively. Further, the positively charged particlescontinue to be delivered and transferred.

Further, though not shown in FIG. 14, a DC positive voltage may beapplied to a substrate to be processed W from a DC power source 114. Forexample, this voltage may be set within the range of 100 V to 3000 V.The positive voltage is applied prior to the RF power, and stopped priorto transferring the substrate W to be processed into a neighboringchamber from the chamber 10, same as the case where the negative voltageis applied to the charging electrode (particularly, the upper chargingelectrode 102). By applying the positive voltage to the substrate W tobe processed, particles charged positively by a charging effect of theaforementioned charging electrode are repulsed from the substrate W tobe processed by Columbic force, so that falling onto the substrate W tobe processed can be completely prevented.

Next, an operation and effect obtained by applying the positive voltageto the substrate W to be processed will be discussed with reference toFIG. 15. FIG. 15 typically shows particle trajectories obtained in areal-time measurement by the particle measurement equipment (FIG. 4),similar to FIG. 5. As shown in FIG. 5, a particle charging region 76 isformed between a plasma PZ and an insulator 70 a (100) on a surface sideof a central charging electrode 102A and a plurality of particletrajectories 92 is observed in this region 76. Here, an electrode plate56 is disposed on the central charging electrode 102A embedded in aninsulator 70 b (100). Meanwhile, the particles falling into thesubstrate W to be processed, which is mounted on an insulator 40 b of asurface of an electrode 40 a, are subject to a repulsive force from thesurface of the substrate W to be processed and leave particletrajectories 120 between the plasma PZ and the substrate W to beprocessed. As mentioned above, the positively charged particles reachingthe substrate W to be processed are repulsed from the substrate W to beprocessed and the plasma PZ, and finally pushed aside the sidewall partof the chamber 10. Further, the positively charged particles aregravitationally accelerated downward along the flow of the exhaust gasand pass through the baffle plate 22 to thereby be exhausted from thechamber 10 through an exhaust port 24. Therefore, it is possible toremove and discharge the particles generated within the chamber 10, moreefficiently.

Meanwhile, in the second and the third embodiment, the plasma etchingwas performed on the silicon oxide film in the same manner as the firstembodiment, by operating the particle removal apparatus of the presentinvention. As a result, a superior in-surface uniformity of the siliconoxide film in the semiconductor wafer (silicon substrate) correspondingto the substrate to be processed and the particle removal effect couldbe confirmed.

In the aforementioned embodiment, the electrode for positively chargingthe particle may be installed in a desired area inside the chamber 10,separately. In particular, the charging electrode 106 in the sidewallpart of the chamber can be divided into a plurality of regions as wellas the charging electrodes 102A and 102B of a shower head 38 side. Inthis case, by properly controlling a value of the negative voltageapplied to each of the divided charging electrodes or an applicationtiming, and drift transferring or delivering, the particles may bedischarged efficiently from the chamber. Further, the control unit foradjusting and controlling these charging electrodes may be collected onone part.

Further, it can be configured such that the electrode for positivelycharging the particle is equipped only in the inner wall of the ceilingof the chamber 10, or only in the sidewall of the chamber 10. Meanwhile,the method for applying the positive potential to the substrate W to beprocessed or the method for applying the negative voltage to the baffleplate 22 may be applied to the third embodiment. Further, the method forapplying the positive potential to the substrate W to be processedand/or the method for applying the negative voltage to the baffle plate22 may be applied to the first and the second embodiment.

In the second to fourth embodiments, a deposition shield may be used asan example of the second charging electrode 106 installed in thesidewall of the chamber, as disclosed in international publication WO00/075972, wherein the deposition shield is made of aluminum whosesurface is alumite treated. In this case, an inner part, where alumitetreatment is not performed, in the deposition shield serves as thesecond charging electrode.

In the aforementioned embodiments, the negative voltage is applied tothe charging electrode installed in the inner wall of the chamber fromthe DC power source, in order to form the particle charging region.However, the present invention is not limited thereto, and the highfrequency may be applied to the charging electrode installed in theinner wall of the chamber from the high frequency power source viacapacitance coupling. In such a method, the ion sheath region formedabove the plasma PZ may be used as the particle charging region byincreasing the field intensity therein.

In the present invention, the particles generated within the plasmaprocessing apparatus are positively charged, and the positively chargedparticles are discharged from the chamber by a drift delivering or atransferring method. However, a particle negatively charged by anelectron in the plasma may exist depending on a plasma processingcondition. In such a case, a device for collecting the negativelycharged particle may be additionally installed in the configuration ofthe present invention. The device for collecting the negatively chargedparticle can be configured such that an electrode, to which the positivevoltage is applied, is equipped in a region, where the negativelycharged particle is generated, inside the chamber.

While the invention has been shown and described with respect to thepreferred embodiments, it will be understood by those skilled in the artthat various changes and modifications may be made without departingfrom the spirit and scope of the invention as defined in the followingclaims. For example, in the aforementioned parallel plate typeelectrode, the cathode coupling mode is only an example. In addition,the present invention may be applied to an anode coupling mode or aplasma producing method having a various type of electrodes other thanthe parallel plate type electrode. But, in case of the aforementionedhelicon wave plasma generation, ECR plasma generation, or ICP plasmageneration, it must be configured such that an installing place of thecharging electrode depends on a configuration of the apparatus, so thatthere is no disturbance of the produced plasma and an ion sheath regionhaving a high field intensity is formed. Further, the present inventionmay be applied to a film forming such as PECVD (Plasma Enhanced CVD), aplasma washing of a substrate to be processed, a plasma cleaning of aninner wall of the chamber, or the like. Still further, the substrate tobe plasma processed is not limited to the semiconductor substrate, but aglass substrate, which is used as LCD substrate, PDP substrate, or thelike, may be employed.

Effects of the Invention

As mentioned above, in the present invention, particles generated withina chamber of a plasma processing apparatus are charged positively bypositive ions of an ion sheath region, and guided towards a gas exhaustport of the plasma processing apparatus via an object of a negativepotential forming the ion sheath region or a space between an inner wallof the chamber and a plasma. In accordance with the present invention,the particles generated within the chamber can be discharged and removedfrom the chamber with high efficiency. Further, a particle removalapparatus of the present invention can be readily applied to a practicaluse, since there is no plasma disturbance or metal contamination and aconfiguration thereof is simple.

1. A method of removing particles from a chamber of a plasma processingapparatus, wherein the chamber is connected to a gas exhaust port and aplasma of a processing gas is generated in the chamber to plasma processa substrate to be processed, the method comprising: positively chargingparticles generated within the chamber by attracting positive ionstoward an ion sheath region formed in a region other than the vicinityof the substrate to be processed; guiding positively charged particlestowards the gas exhaust port via the ion sheath region; and dischargingthe positively charged particles from the chamber through the gasexhaust port, wherein the positively charging particles, the guidingpositively charged particles, and the discharging the positively chargedparticles are performed during plasma processing, wherein during theplasma processing, a negative potential is applied to a surface of anobject disposed adjacent to the ion sheath region in order to attractpositive ions and the positively charged particles towards the surfaceof the object, and wherein the object adjacent to the ion sheath regionis electrically divided into a plurality of regions depending on adistance from the gas exhaust port, and independent negative potentialsare applied to the respective regions.
 2. The method of claim 1, whereina negative potential with a first absolute value is applied to a firstregion among said plurality of regions and a negative potential with asecond absolute value is applied to a second region among said pluralityof regions, the first absolute value being greater than the secondabsolute value and the first region being closer to the gas exhaust portthan the second region is.
 3. The method of claim 2, wherein a number ofnegative potentials with different pulse phases are applied to theplurality of regions, to transfer the positively charged particlestowards the gas exhaust port.
 4. The method of claim 1, wherein a numberof negative potentials with different pulse phases are applied to theplurality of regions, to transfer the positively charged particlestowards the gas exhaust port.
 5. A method of removing particles from achamber of a plasma processing apparatus, wherein the chamber isconnected to a gas exhaust port and a plasma of a processing gas isgenerated in the chamber to plasma process a substrate to be processed,the method comprising: positively charging particles generated withinthe chamber by positive ions of an ion sheath region formed in a regionother than the vicinity of the substrate to be processed; guidingpositively charged particles towards the gas exhaust port via the ionsheath region; and discharging the positively charged particles from thechamber through the gas exhaust port, wherein a negative potential isapplied to a surface of an object disposed adjacent to the ion sheathregion in order to attract positive ions and the positively chargedparticles towards the surface of the object, and wherein the objectadjacent to the ion sheath region is electrically divided into aplurality of regions depending on a distance from the gas exhaust port,and independent negative potentials are applied to the respectiveregions.
 6. The method of claim 5, wherein a negative potential with afirst absolute value is applied to a first region among said pluralityof regions and a negative potential with a second absolute value isapplied to a second region among said plurality of regions, the firstabsolute value being greater than the second absolute value and thefirst region being closer to the gas exhaust port than the second regionis.
 7. The method of claim 6, wherein a number of negative potentialswith different pulse phases are applied to the plurality of regions, totransfer the positively charged particles towards the gas exhaust port.8. The method of claim 5, wherein a number of negative potentials withdifferent pulse phases are applied to the plurality of regions, totransfer the positively charged particles towards the gas exhaust port.